A process of manufacturing a semiconductor device may include a process of forming a thin film on a substrate a process chamber at a predetermined temperature and a process of cleaning an interior of the process chamber by supplying a cleaning gas into the process chamber after the process of forming the thin film is performed. This cleaning process may remove deposits including a thin film deposited in the process chamber during the process of forming the thin film on the substrate.
In some cases, during the process of forming the thin film, deposits may be easily deposited on other members that are located out of a processing region in the substrate and at a relatively low temperature within the process chamber. However, it is difficult for a cleaning gas to reach such members located out of the processing region in the substrate. This may result in low cleaning efficiency and incomplete removal of the deposits formed on the members. Repeated substrate processing while the deposits are not completely removed may deteriorate the in-plane uniformity in thickness or in quality of the thin film formed on the substrate.